Tooth of an alsatian dog discovered a mile from Stonehenge, Wiltshire. Photograph: University of Buckingham/PA

Archaeologists have discovered evidence of what they believe is the earliest known journey in British history: a 250-mile trip from York to Wiltshire made 7,000 years ago by a Mesolithic hunter-gatherer and his dog.

Scientific investigation of a dog’s tooth found at a site one mile from Stonehenge has thrown up a number of exciting discoveries, said archaeologist David Jacques, who leads the team digging at an encampment site called Blick Mead.

For one thing, it shows that Mesolithic man was using a domesticated dog, probably for hunting. But more fascinating is that the animal originally came from an area that is now the Vale of York, suggesting the pair made a long, gruelling journey.

Jacques said the findings showed the dog and people with it came to what is now Wiltshire. This is the earliest evidence of a journey that has been unearthed in Britain.

The clinching evidence was found by researchers at Durham University, who carried out an isotope analysis of the tooth enamel, which showed the dog drank water that came from the Vale of York area. They also speculate that the dog would have been roughly the same size, shape and colour of an alsatian, albeit more wolf-like.

Jacques said the Durham analysis was “a world first, it’s a big deal,” that substantially increased what archaeologists know about Blick Mead. “It is very hazy and this evidence just makes the glass slightly less dark, it is a significant movement forwards,” he said.

Previously, artefacts had been found which implied Mesolithic man had travelled long distances to get to the site. Jacques and his team believe people were coming to the spot over a near 4,000-year period, from 7900BC to 4000BC.

“It is an amazing sequence,” he added. “There is nothing like it in Europe and now we’ve got this evidence from the dog you start to piece it together. You can see that this place seems to have special to not just local people, it seems to have been drawing in people from long distances away and the sort of distances you would not expect for mobile hunter-gatherers.”

Jacques has led University of Buckingham digs at Blick Mead for nearly a decade, believing the area is key to the beginnings of people living in Britain because evidence of occupancy covers such a long period of time.

Other discoveries include evidence of Mesolithic people feasting on huge oxen, known as aurochs, salmon, trout, hazelnuts and even frog’s legs, about eight millennia before they became a French staple.

Jacques believes Blick Mead is crucial to our understanding of the stone circle at Stonehenge, erected in the late Neolithic period, at about 2500BC

“Discoveries like this give us a completely new understanding of the establishment of the ritual landscape and make Stonehenge even more special than we thought we knew it was,” said Jacques.

It raises the question of why people would travel such long distances to get to the site. “It makes us wonder if this place is a hub point, a really important place for the spread of ideas, new technologies and probably genes,” said Jacques.

“You have small dispersed populations of people in Britain and people are probably getting it together and families are coming out of that. In a sense it is probably quite a multicultural environment.”

The Blick Mead site is close to the busy A303 and only 100 metres from the site of a proposed 1.8-mile tunnel, which would remove the road from the Stonehenge site.

Jacques is firmly against a tunnel, fearing it could alter the water table and make it impossible to continue digging at Blick Mead. “It would be devastating if the tunnel obliterated our chance of piecing together the jigsaw to explain why Stonehenge was built,” he said.

Examination of a trench in Blick Mead has led to the discovery of a charred toad’s leg, bones of trout or salmon as well as the remains of cooked aurochs. Photograph: University of Buckingham/PA

The tunnel is supported by the National Trust and Historic England, which believe the road is a blight.

Andy Rhind-Tutt, chairman of Amesbury Museum and Heritage Trust, said the discoveries were rewriting the history books of Mesolithic Britain. “Blick Mead is without doubt one of the greatest national discoveries ever made in the Stonehenge landscape.

“As we edge towards a road improvement plan that could see a disastrous, ineffective tunnel, I desperately hope Historic England and the National Trust recognise what a key site this is and ensure it is protected and preserved so that we can carry on unlocking the history of Stonehenge.”

Historic England said any tunnel was likely to be well away from the Blick Mead site.

Phil McMahon, inspector of ancient monuments for Historic England in the south west said: “There’s no scheme available yet to understand the exact impacts of any road improvement proposal.

“But from our work on possible tunnel locations advising Department for Transport and Highways England over the past two and a half years, we understand that any tunnel scheme is likely to be well away from the Blick Mead site.”